This invention relates to processes for the manufacture of semiconductor devices and, more specifically, to a fast recovery diode (FRED) that is manufactured using a reduced number of masking steps.
Typically, the process for fabricating a FRED requires four or five masking steps. A first masking step defines the termination and P-type anode regions. A second masking step defines the contact region, and then a third masking step defines the deposited metal. Subsequently, a passivation layer is defined using a fourth masking step. Additionally, further masking steps may be incorporated for defining an equipotential ring (EQR) as well as for defining an enhancement termination implant.
Each of these masking steps may include a critical mask alignment, which adds manufacturing time and expense. Furthermore, each of the masking steps provides a possible source of device defects, as are caused by particles attached to the mask from the photoresist.
It is therefore desirable to minimize the number of critical alignments necessary as well as to reduce the number of masking steps to improve the manufacturing yield and reduce the manufacturing cost.